This invention relates generally to a rotary cam for a bending die, and specifically to a failsafe device for properly positioning the rotary cam.
Bending dies are known in the art that produce negative angles in a sheet metal work piece. A negative angle is an angle in the work piece that cannot be formed by the simple vertical movement of the upper die portion. In order to produce the negative angle a rotary cam is used in concert with a bending cam. The rotary cam moves into position such that the bending cam can bend the work piece. After the desired forming of the work piece, the rotary cam is rotated to a release position to allow removal of the work piece.
Typically, a pneumatic actuator is utilized to move the rotary cam between bending and released positions. If the rotary cam is not in the proper position as the bending die is closed undesirable contact between the bending cam and the rotary cam can occur.
It is known to provide a failsafe element to prevent contact between the bending cam and the rotary cam. Such fails safe elements include a cantilever-mounted roller on the rotary cam. The roller engages a cam surface moving with the driven die portion to move the rotary cam to the bending position. The cam surface and moving die portion are usually driven at a high speed. The high speed causes high forces upon contact between the roller and the cam surface. The cantilevered roller is often damaged due to the high forces between the roller and the cam surface.
Accordingly, it is desirable to design a dependable and durable rotary cam failsafe device for properly positioning the rotary cam of a bending die.